GaryW Posted February 19 Share Posted February 19 (edited) 2 hours ago, Nigel R said: If I'm honest, there was no way a healthy 4 cell nimh pack (and a decent switch with good wiring) would have dropped below the original operating voltage range - providing the pack was not overstressed. I Disagree..... A friend built a " Brand New " 72" wingspan Mustang a few years back with mechanical retracts & Retract Servo the old school way with him being of senior years so to speak,,, everything installed brand shiny new including the RX Battery and working correctly at the time of doing his pre-flight checks only to then proceed to take off and complete 2 circuits of the flying field for his shiny new plane to then dive for the ground to then mad a mad attempt to dig a tunnel to China....... Later on inspection is was discovered the 4.8v 3000mah Sub C RX Battery had failed due to a stalled Retract Servo that didn't switch off at the end of travel once the retracts have lifted up into the wing killing the RX Battery to dead flat in less than 30 seconds from take off....... Since then he now runs a separate battery for retracts in all his models than have retractable undercarraige Edited February 19 by GaryW Quote Link to comment Share on other sites More sharing options...
Jon H Posted February 19 Share Posted February 19 17 hours ago, Stuart Z said: Fortunately they were both easy landing aircraft and the strip was maintained well so no “hard” landings. Still have one set of retracts and still have the servos, who knows, one day! What about a hard takeoff? I have had retract pins bent on takeoff after hitting a bump of some kind. On one occasion some mud accumulated and prevented smooth retraction as well. Quote Link to comment Share on other sites More sharing options...
steve too Posted February 19 Share Posted February 19 1 hour ago, GaryW said: Later on inspection is was discovered the 4.8v 3000mah Sub C RX Battery had failed due to a stalled Retract Servo that didn't switch off at the end of travel once the retracts have lifted up into the wing killing the RX Battery to dead flat in less than 30 seconds from take off....... For that to be the case, the battery would have to be effectively flat at the start of the flight. A Hitec HS-75BB (a typical mechanical retract servo) has a stall current of 1A. 1A or even 3A is not going to flatten a charged subC in 30s or significantly impact the receiver voltage. 4 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 19 Share Posted February 19 2 hours ago, GaryW said: I Disagree..... A friend built a " Brand New " 72" wingspan Mustang a few years back with mechanical retracts & Retract Servo the old school way with him being of senior years so to speak,,, everything installed brand shiny new including the RX Battery and working correctly at the time of doing his pre-flight checks only to then proceed to take off and complete 2 circuits of the flying field for his shiny new plane to then dive for the ground to then mad a mad attempt to dig a tunnel to China....... Later on inspection is was discovered the 4.8v 3000mah Sub C RX Battery had failed due to a stalled Retract Servo that didn't switch off at the end of travel once the retracts have lifted up into the wing killing the RX Battery to dead flat in less than 30 seconds from take off....... Since then he now runs a separate battery for retracts in all his models than have retractable undercarraige Apples and oranges, and not the kind of scenario I described. Take off damage lead to mechanical failure with a subsequent electrical overload. As noted, separating the retract power supply would have mitigated this risk and allowed a controlled landing. 2 Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 1 hour ago, steve too said: For that to be the case, the battery would have to be effectively flat at the start of the flight. A Hitec HS-75BB (a typical mechanical retract servo) has a stall current of 1A. 1A or even 3A is not going to flatten a charged subC in 30s or significantly impact the receiver voltage. you are entitled to you view however that wasnt the case as the rx battery was fully changed as the battery checker showed in the pre-flight checks Quote Link to comment Share on other sites More sharing options...
steve too Posted February 19 Share Posted February 19 1 hour ago, GaryW said: you are entitled to you view however that wasnt the case as the rx battery was fully changed as the battery checker showed in the pre-flight checks Discharge curve for a 3300mAh subC (from a GP datasheet). 3 Quote Link to comment Share on other sites More sharing options...
RottenRow Posted February 19 Share Posted February 19 1 hour ago, steve too said: Discharge curve for a 3300mAh subC (from a GP datasheet). Indeed. To discharge a 3Ah battery from fully charged in 30 seconds would have meant an average current of 360A. More than enough to cause the insulation on the wiring to melt, and probably desolder the receiver board as well, and quite likely start a fire. Some battery checkers can give incorrect results. Brian. 4 Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 19 Share Posted February 19 Glad I don't fly at Gary Ws club with all those planes crashing due to flat rx batteries, and dodgy radio gear........ you'd need a hard hat! 3 Quote Link to comment Share on other sites More sharing options...
leccyflyer Posted February 19 Share Posted February 19 4 hours ago, GaryW said: you are entitled to you view however that wasnt the case as the rx battery was fully changed as the battery checker showed in the pre-flight checks This wasn't the checker was it? 😉 1 6 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 19 Share Posted February 19 You sometimes have to take other modellers' claims with a pinch of salt. A couple of examples come to mind - the first, a nice kit built FW190 that I was asked to test fly... The owner had a bit of a reputation for forgetting to charge his batteries so I asked for confirmation and he assured me that he had not only fully charged his receiver pack but had checked it prior to assembling the model and it was showing as fully charged. Two and a half circuits later, it was lying in a pile of bits after a rapid unscheduled disassembly. On investigation, I found that the battery was flat. Binding retracts? No - it had a 5 cell pack which had been charged - and later checked - as a 4 cell one. The second was a beginner who kept turning up with batteries that lasted only a flight or so before the servos were noticeably slow and failed a voltage test. Repeated assurances that he'd charged the packs fully the night before...except that he eventually revealed that his definition of a full charge was an hour on the dumb wall charger supplied with his radio. 1 Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 (edited) A stalled retract servo will draw a high current . This can flatten a battery very quickly which will of course result in a complete loss of control if the battery also supplies the receiver.... A high capacity receiver battery will only allow more time before a loss of control occurs so this is only a partial answer to this problem. A much better solution is to provide a separate battery to power the retract servo alone. This means that the receiver and flight control servos will be unaffected by any problems occurring with the servo operated retract system. Edited February 19 by GaryW Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 56 minutes ago, GrumpyGnome said: Glad I don't fly at Gary Ws club with all those planes crashing due to flat rx batteries, and dodgy radio gear........ you'd need a hard hat! Please direct me to where I said anything about planes crashing at my club field seems my brain has had another brain fart and my cheap specsavers glasses once again appear to be defective and letting me down...... Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 (edited) 29 minutes ago, leccyflyer said: This wasn't the checker was it? 😉 Pass.. But good try.......... Moving on now Edited February 19 by GaryW Quote Link to comment Share on other sites More sharing options...
Outrunner Posted February 19 Share Posted February 19 27 minutes ago, GaryW said: Please direct me to where I said anything about planes crashing at my club field seems my brain has had another brain fart and my cheap specsavers glasses once again appear to be defective and letting me down...... 8 hours ago, GaryW said: NO WAY wud I trust RadioMaster seen to many people have planes and helis pile them self into the ground in a mad attempt to dig their way to Australia.. 2 within the last few months who were flying on Radiomaster.. also over the years seen the same happen with Taranis , Flysky & FrSky transmitters 1 Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 (edited) 13 minutes ago, Outrunner said: Doesn't say that happened at my club field at all anywhere... I do visit other flying sites aswell with friends from time to time.... Again moving on Edited February 19 by GaryW Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 19 Share Posted February 19 (edited) 1 hour ago, GaryW said: Please direct me to where I said anything about planes crashing at my club field seems my brain has had another brain fart and my cheap specsavers glasses once again appear to be defective and letting me down...... In the thread about someone buying a new tx - you stated you'd seen a number of crashes caused by Taranis, Flysky and Frsky equipment.... Ah, not at your own club. OK. I see I was beaten to responding 🙂 Edited February 19 by GrumpyGnome Quote Link to comment Share on other sites More sharing options...
MattyB Posted February 19 Share Posted February 19 (edited) 10 minutes ago, GrumpyGnome said: In the thread about someone buying a new tx - you stated you'd seen a number of crashes caused by Taranis, Flysky and Frsky equipment.... Ah, not at your own club. OK. Remember, this is practically the only flyer in the country who appears to be in love with the idea of RID, despite the fact the regs as proposed pose a significant risk of his flying site being barred from use. I wouldn't waste your time expecting a fully reasoned rationale from someone who believes an increased volume of unenforceable regulations results in increased compliance... Edited February 19 by MattyB 1 Quote Link to comment Share on other sites More sharing options...
GaryW Posted February 19 Share Posted February 19 (edited) 34 minutes ago, MattyB said: Remember, this is practically the only flyer in the country who appears to be in love with the idea of RID, despite the fact the regs as proposed pose a significant risk of his flying site being barred from use. I wouldn't waste your time expecting a fully reasoned rationale from someone who believes an increased volume of unenforceable regulations results in increased compliance... And once again here come the playground know it alls to strike again... I'm so glad Matty that you seem to know more than clubs do in what they will be banned from in future years to come,, many of us shud have a long detailed chat with our clubs and respective committees respectively as they clearly lack your superior knowledge experience and qualifications to say how clubs will be effected in the long term........ Long past getting boring now And once again..... Now moving on Edited February 19 by GaryW Quote Link to comment Share on other sites More sharing options...
Philip Lewis 3 Posted February 19 Share Posted February 19 1 hour ago, GaryW said: And once again here come the playground know it alls to strike again... I'm so glad Matty that you seem to know more than clubs do in what they will be banned from in future years to come,, many of us shud have a long detailed chat with our clubs and respective committees respectively as they clearly lack your superior knowledge experience and qualifications to say how clubs will be effected in the long term........ Long past getting boring now And once again..... Now moving on Yes please do! 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 20 Share Posted February 20 This isn’t aimed at anyone in particular but this thread is getting rather bad natured so just a reminder that we’re a friendly forum and we should refrain from making personal observations on other members’ opinions. By all means post opposing views but there’s a point where simply restating opinions gets pointless. Don’t post merely to provoke a reaction either! 5 Quote Link to comment Share on other sites More sharing options...
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